Fig. 1.

Orai1 KO mice have reduced milk Ca²⁺. (A) TG-induced Ca²⁺ entry in mammary luminal cells isolated from Orai1^+/+ (n = 82 cells) and Orai1^−/− (n = 86 cells) mice. Cells were bathed in nominally Ca²⁺-free HBSS supplemented with 1,2-bis(o-aminophenoxy)ethane-N,N,N′, N′-tetraacetic acid (BAPTA, 500 μM) for 2 min and treated with TG (2 μM) to deplete ER Ca²⁺ stores before Ca²⁺ readdition (2 mM). Peak ratio responses to (B) TG (150–270 s) and (C) Ca²⁺ readdition (1,000–1,180 s). Total Ca²⁺ and protein concentrations in milk collected from (D and E) lactating (day 3) Orai1^−/− mice versus control genotypes and (F and G) mice with conditional deletion of Orai1 in the mammary epithelia (Orai1^fl/−;MMTV-Cre) versus control genotypes (n = 3–4 mice). Data represent mean ± SEM; *P < 0.05, Student’s t test (B and C) or one-way ANOVA with Bonferroni posttests (D–G).